Honeywell C645A-E Product Data page 5

The C645E1002 Distillate Fuel Oil Pressure Switch is the
same as the C645A1006 Gas Pressure Switch except that it
does not have a 0.015 in. (0.38 mm) diameter (nominal)
orifice in its 1/4 in. NPT main (high pressure) connection.
(This orifice is required in a C645A Gas Pressure Switch to
restrict gas leakage, but it is too small for oil applications.)
The C645E1002 has a 0.125 in. (3.18 mm) diameter
(nominal) opening in its 1/4 in. NPT main connection into its
pressure chamber.
CAUTION
Vent the bleed tapping back to the oil supply tank—
not to the combustion chamber.
Wiring
Disconnect power supply before connecting wiring to prevent
electrical shock and equipment damage.
All wiring must agree with applicable codes, ordinances, and
regulations. An opening is provided to accommodate rigid
conduit or armored cable for line voltage operation (Fig. 3
and 4). Do not overload the switch contacts (see Switch
Ratings in Specifications section). The switching schematic is
shown in Fig. 5.
SET POINT
ADJUSTMENT
SCREW
OPENING
FOR 1/2 INCH
CONDUIT
MICRO
SWITCH
MANUAL RESET LEVER
ON LOCKOUT MODELS ONLY
Fig. 3. C645A,B,D with cover removed.
SCALE
BLEED
PLATE
FITTING
COVER
SCREW
M7560
5
C645A-E PRESSURE SWITCHES
MANUAL RESET
LEVER
ON LOCKOUT
MODELS ONLY
COVER
SCREW
SCALE BLEED
PLATE
FITTING
Fig. 4. C645C with cover removed.
W
B
R
1 C645A,C,D BREAKS R-W, MAKE R-B ON PRESSURE FALL.
MANUAL RESET MODELS LOCK OUT.
2 C645B BREAKS R-B, MAKES R-W ON PRESSURE RISE
AND LOCKS OUT.
Fig. 5. Schematic showing switch in zero
pressure condition.
OPENING
FOR 1/2 INCH
CONDUIT
SET POINT
ADJUSTMENT
SCREW
M7561
2
1
M7565
60-2159—8